Polyamides such as nylon are generally high strength, hard polymers due at least in part to the presence of a strong hydrogen bond with nitrogen and a strong covalent bond between carbon and oxygen. These polymers are used in a wide variety of applications such as gears, machine parts, rope, fibers, films, sheets and other applications where high strength is desired. Common examples of polyamides include the nylons, which are a family of polyamide polymers characterized by the presence of the amide group (--CONH). The structure of an example of a polyamide, nylon 66, is shown below: ##STR1##
In contrast to the polyamides, halogenated polymers, which include a halogen element (i.e., fluorine, chlorine, bromine, iodine or astatine), are generally relatively low strength materials. Common examples of halogenated polymers include the fluorocarbons, which include any of a number of organic compounds analogous to hydrocarbons in which the hydrogen atoms have been replaced by fluorine. Halogenated polymers are generally exploited for their low friction properties in applications such as chemical wear, seals, bearings, release films and gaskets. For example, in polytetrafluoroethylene (TEFLON), the C--F bond is so strong that there is little bonding to external substances, which accounts for the low coefficient of friction. The structure of TEFLON is shown below: ##STR2##
Many engineering applications would benefit from a material combining the high strength of polyamides and the low friction properties of halogenated polymers. For example, gears, bushings and release films made of TEFLON have the requisite low friction properties but have limited useful lifetimes due to their relatively low strengths. Moreover, in contrast to polyamides, halogenated polymers have very low melt strengths and thus are not suitable for many formation processes such as blown film extrusion. A combination of polyamide and halogenated polymers therefore poses the potential for significant benefits in terms of optimizing mechanical properties and allowing for a wide variety of processing procedures.